/*
 * mbuf.h
 *		Memory buffer operations.
 *
 * Copyright (c) 2005 Marko Kreen
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *	  notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *	  notice, this list of conditions and the following disclaimer in the
 *	  documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.	IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 * contrib/pgcrypto/mbuf.h
 */

#ifndef __PX_MBUF_H
#define __PX_MBUF_H

typedef struct MBuf MBuf;
typedef struct PushFilter PushFilter;
typedef struct PullFilter PullFilter;
typedef struct PushFilterOps PushFilterOps;
typedef struct PullFilterOps PullFilterOps;

struct PushFilterOps {
    /*
     * should return needed buffer size, 0- no buffering, <0 on error if NULL,
     * no buffering, and priv=init_arg
     */
    int (*init)(PushFilter* next, void* init_arg, void** priv_p);

    /*
     * send data to next.  should consume all? if null, it will be simply
     * copied (in-place) returns 0 on error
     */
    int (*push)(PushFilter* next, void* priv, const uint8* src, int len);
    int (*flush)(PushFilter* next, void* priv);
    void (*free)(void* priv);
};

struct PullFilterOps {
    /*
     * should return needed buffer size, 0- no buffering, <0 on error if NULL,
     * no buffering, and priv=init_arg
     */
    int (*init)(void** priv_p, void* init_arg, PullFilter* src);

    /*
     * request data from src, put result ptr to data_p can use ptr from src or
     * use buf as work area if NULL in-place copy
     */
    int (*pull)(void* priv, PullFilter* src, int len, uint8** data_p, uint8* buf, int buflen);
    void (*free)(void* priv);
};

/*
 * Memory buffer
 */
MBuf* mbuf_create(int len);
MBuf* mbuf_create_from_data(uint8* data, int len);
int mbuf_tell(MBuf* mbuf);
int mbuf_avail(MBuf* mbuf);
int mbuf_size(MBuf* mbuf);
int mbuf_grab(MBuf* mbuf, int len, uint8** data_p);
int mbuf_steal_data(MBuf* mbuf, uint8** data_p);
int mbuf_append(MBuf* dst, const uint8* buf, int cnt);
int mbuf_rewind(MBuf* mbuf);
int mbuf_free(MBuf* mbuf);

/*
 * Push filter
 */
int pushf_create(PushFilter** res, const PushFilterOps* ops, void* init_arg, PushFilter* next);
int pushf_write(PushFilter* mp, const uint8* data, int len);
void pushf_free_all(PushFilter* mp);
void pushf_free(PushFilter* mp);
int pushf_flush(PushFilter* mp);

int pushf_create_mbuf_writer(PushFilter** mp_p, MBuf* mbuf);

/*
 * Pull filter
 */
int pullf_create(PullFilter** res, const PullFilterOps* ops, void* init_arg, PullFilter* src);
int pullf_read(PullFilter* mp, int len, uint8** data_p);
int pullf_read_max(PullFilter* mp, int len, uint8** data_p, uint8* tmpbuf);
void pullf_free(PullFilter* mp);
int pullf_read_fixed(PullFilter* src, int len, uint8* dst);

int pullf_create_mbuf_reader(PullFilter** pf_p, MBuf* mbuf);

#define GETBYTE(pf, dst)                           \
    do {                                           \
        uint8 __b;                                 \
        int __res = pullf_read_fixed(pf, 1, &__b); \
        if (__res < 0)                             \
            return __res;                          \
        (dst) = __b;                               \
    } while (0)

#endif /* __PX_MBUF_H */
